TIME COURSE OF RECOVERY OF BETA-ADRENOCEPTORS AND ALPHA-1-ADRENOCEPTORS IN EXPERIMENTAL ASTHMA

1. The time course of recovery of reduced β‐adrenoceptors caused by ovalbumin (OA) challenge was investigated using guinea‐pigs. 2. The effects of prednisolone on the recovery time course were also evaluated. 3. β‐ and α1‐receptor assays were performed using lung membranes. Adenylate cyclase activity was also measured. 4. OA challenge reduced the number of β‐adrenoceptors by 35%, and a significant decrease (13%) persisted for 7 days. The number of β‐adrenoceptors recovered after 14 days. 5. OA challenge elevated the number of α1‐adrenoceptors. A significant increase (24%) was observed after 7 days, and it took a further 7 days for the recovery. 6. After OA challenge there was a significant decrease in adenylate cyclase activity after 7 days, which recovered after a further 7 days. 7. Inhalation of prednisolone accelerated the recovery of β‐adrenergic responsiveness, though it did not affect the recovery of the number of α1‐adrenoceptors. Prednisolone inhalation also elevated β‐adrenergic responsiveness in non‐asthmatic subjects. 8. It is concluded that reduced β‐adrenergic responsiveness caused by OA challenge persisted for 7 days and recovered after a further 7 days. Steroid hormone increased β‐adrenoceptors. Copyright © 1990, Wiley Blackwell. All rights reserved